Freeze fracture machine

ABSTRACT

A freeze fracture machine (100) comprises a vacuum chamber (110); a sample receptacle (160) for receiving a sample to be processed and a knife receptacle (150) for receiving a knife (110) for processing of the sample arranged in the vacuum chamber (155); a transfer lock (130) on the vacuum chamber (110) through which a sample and a knife (155) are introducible into the vacuum chamber (155) and positionable in the vacuum chamber (110) by means of a positioning apparatus (135); the sample and the sample receptacle (160) being positionable with respect to one another such that the sample is mountable on the sample receptacle (160) by means of the positioning apparatus (135); and the knife (155) and the knife receptacle (150) being positionable with respect to one another such that the knife (155) is mountable on the knife receptacle (150) by means of the positioning apparatus (135).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of German patent application number 102014 118 801.2 filed Dec. 17, 2014, the entire disclosure of which isincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a freeze fracture machine having avacuum chamber, and to a method for introducing a sample and a knifeinto a vacuum chamber of a freeze fracture machine of this kind.

BACKGROUND OF THE INVENTION

Freeze fracture machines serve for the processing of frozen samples suchas tissue samples. The frozen sample can be sectioned or fractured, bymeans of a knife, in a vacuum chamber of the freeze fracture machine.The vacuum chamber or vacuum serves in particular to eliminate waterthat could contaminate the sample. In addition, both the sample and theknife are cooled, usually with liquid nitrogen, so that the frozensample does not become heated during processing.

A viewing window, through which the sample to be processed is visible,is usually provided in the freeze fracture machine or in the vacuumchamber thereof. A microscope can furthermore be provided, for example,if very small samples are to be processed.

A transfer lock, through which the sample can be introduced into orremoved from the vacuum chamber without interrupting the vacuum, can beprovided on the freeze fracture machine for the introduction and removalof a sample.

In order to introduce or remove a knife, for example in order to changea knife type or replace a contaminated knife, it has hitherto beennecessary to break the vacuum, aerate the vacuum chamber, and change theknife via the viewing window or a corresponding door. It isdisadvantageous here that as a result of the aeration and re-evacuation,the knife changing procedure takes a very long time. In addition, theentire vacuum chamber must be heated to room temperature so that theknife can be changed.

It is therefore desirable to describe a capability for faster andsimpler changing of a knife and a sample in the context of a freezefracture machine.

SUMMARY OF THE INVENTION

A freeze fracture machine and a method for introducing a sample and aknife into a vacuum chamber of a freeze fracture machine are proposedaccording to the present invention.

A freeze fracture machine of the present invention generally comprises avacuum chamber; a sample receptacle for receiving a sample to beprocessed, the sample receptacle being arranged in the vacuum chamber; aknife receptacle for receiving a knife provided for processing of thesample, the knife receptacle being arranged in the vacuum chamber; atransfer lock through which the sample and the knife are introducibleinto the vacuum chamber; and a positioning apparatus provided on thevacuum chamber, the positioning apparatus being operable to introducethe sample and the knife into the vacuum chamber through the transferlock and position the sample and the knife in the vacuum chamber. Thesample and the sample receptacle are positionable with respect to oneanother such that the sample is mountable on the sample receptacle byoperation of the positioning apparatus. The knife and the knifereceptacle are positionable with respect to one another such that theknife is mountable on the knife receptacle by operation of thepositioning apparatus.

A method for introducing a sample and a knife into a vacuum chamber of afreeze fracture machine according to the present invention generallycomprises the steps of introducing the sample via the transfer lock intothe vacuum chamber and mounting the sample on the sample receptacle byoperating the positioning apparatus; and introducing the knife via thetransfer lock into the vacuum chamber and mounting the knife on theknife receptacle by operating the positioning apparatus.

Advantageous embodiments are the subject matter of the description thatfollows.

ADVANTAGES OF THE INVENTION

A freeze fracture machine according to the present invention comprises avacuum chamber; a sample receptacle for receiving a sample to beprocessed, and a knife receptacle for receiving a knife provided forprocessing of the sample, are arranged in the vacuum chamber. Providedon the vacuum chamber is a transfer lock through which a sample and aknife are introducible into the vacuum chamber and positionable in thevacuum chamber by means of a positioning apparatus.

The sample and the sample receptacle are positionable with respect toone another in such a way that the sample is mountable on the samplereceptacle by means of the positioning apparatus, and the knife and theknife receptacle are positionable with respect to one another in such away that the knife is mountable on the knife receptacle by means of thepositioning apparatus.

A freeze fracture machine of this kind thus makes it possible to changeboth a sample and a knife through one and the same transfer lock. Thishas the advantage that the vacuum chamber does not need to be aeratedand heated either in order to change the sample or in order to changethe knife. A sample change and also, in particular, a knife change canthus be carried out in very quick and uncomplicated fashion.

A “transfer lock” is understood as an opening in the vacuum chamberwhich is closable with a vacuum-tight door (usually embodied as a slidevalve). A vacuum transfer system (ideally a vacuum cryo transfer system)can then be flange-mounted onto such a transfer lock. Once the vacuumtransfer system is evacuated, the door can be opened with no pressureloss or temperature increase in the vacuum chamber. The positioningapparatus can, in particular, be part of a vacuum transfer system ofthis kind. A preferred vacuum cryo transfer system is offered by theApplicant, for example, under the designation EM VCT100.

Preferably the knife receptacle is bringable into a changing position,and in the changing position the knife is mountable on the knifereceptacle. For this purpose the knife receptacle can be displaceable,for example, along a rail or the like. Further displacement mechanisms,by means of which the knife receptacle is displaceable in variousdirections, can likewise be provided. The knife receptacle can thus bebrought into a maximally favorable position relative to the transferlock. In this manner, for example, a transfer lock that has hithertobeen used to to change the sample can thus very easily also be used tochange the knife. A working position in which the knife assumes adesired position for sectioning the sample can be provided, for example,as a further position. Multiple working positions are also conceivable.

Advantageously, a knife holder for immobilizing the knife is mountableon the positioning apparatus, and the knife holder is connectable to theknife receptacle.

This makes possible particularly simple introduction of a knife into thevacuum chamber, since a knife holder can be mounted in particularlysimple fashion on the positioning apparatus, which can be e.g. a sliderod, for example by simply being placed on.

It is advantageous if a sample holder for immobilizing the sample ismountable on the positioning apparatus, the sample holder beingconnectable to the sample receptacle. This makes possible particularlysimple introduction of a sample into the vacuum chamber, since a sampleholder, like the knife holder, is mountable on the positioning apparatusin particularly simple fashion.

Preferably the knife receptacle comprises receiving means forestablishing a connection of the knife holder to the knife receptacle.This makes possible simple and stable mounting of the knife holder. Forexample, the receiving means can be two spaced-apart rails into whichthe knife holder can be inserted.

Advantageously, the sample receptacle comprises receiving means forestablishing a connection of the sample holder to the sample receptacle,the receiving means of the knife holder and of the sample holder inparticular being configured similarly. This on the one hand makespossible simple and stable mounting of the sample holder, as in the caseof the knife receptacle. In addition, if the two receiving means areconfigured similarly, similar holders can be used as sample holders andas knife holders.

It is advantageous if the knife holder comprises fastening means,corresponding to the receiving means of the knife receptacle, which areactuatable by means of the positioning apparatus in order to establishthe connection of the knife holder to the knife receptacle. Suchfastening means can be, for example, bolts impinged upon by springforce. These bolts can then be retracted, for example, by rotating thepositioning apparatus, in particular when it is a slide rod. Afterintroduction into the receiving means of the knife receptacle, thesebolts can then be nonpositively and/or positively connected to thereceiving means.

Preferably the sample holder comprises fastening means, corresponding tothe receiving means of the sample receptacle, which are actuatable bymeans of the positioning apparatus in order to establish the connectionof the sample holder to the sample receptacle, the fastening means ofthe knife holder and of the sample holder in particular being configuredsimilarly. The result is that, as in the case of the knife holder, asimple and secure connection can be established between the samplereceptacle and the sample holder. In particular, similar holders canthus be used as sample holders and knife holders, such that a sample canbe mounted on one holder and a knife on the other holder.

Advantageously, the sample receptacle is arranged at a fixed position inthe vacuum chamber. Particularly simple mounting of the sample on thesample receptacle can thereby be enabled. This furthermore ensures thatthe sample receptacle is always located in the same position, so thataccurately placed processing actions are possible.

It is advantageous if the positioning apparatus is configured todisplace the sample or the knife inside the vacuum chamber along anaxis. This makes possible a simple configuration of the positioningapparatus, for example in the form of a slide rod. Simple changing ofthe knife is thereby enabled, especially in combination with thedisplaceable knife receptacle. Advantageously, the positioning apparatuscomprises a magnetically coupled rotary/slide lead-through for vacuum.This can also be a bellows-sealed or elastomer-sealed rotary/slidelead-through.

Preferably the sample receptacle and/or the knife receptacle comprise aconnector for a coolant. The coolant can be, in particular, liquidnitrogen. The sample receptacle or knife receptacle can comprise, forexample, a copper block by way of which a coolant line can be connectedand through which the coolant is directed.

Continuous cooling of the sample during processing is thereby ensured.

A method according to the present invention serves for introduction of asample and of a knife into a vacuum chamber of a freeze fracture machineaccording to the present invention. At a first point in time the sampleis introduced via the transfer lock into the vacuum chamber and mountedon the sample receptacle by means of the positioning apparatus; and at asecond point in time the knife is introduced via the transfer lock intothe vacuum chamber and mounted on the knife receptacle by means of thepositioning apparatus.

It is thus possible thereby to change both a sample and a knife throughonly one transfer lock. This has the advantage that the vacuum chamberdoes not need to be aerated and heated either in order to change thesample or in order to change the knife. A sample change, and inparticular also a knife change, can thus be carried out in very quickand uncomplicated fashion.

Further advantages and embodiments of the invention are evident from thedescription and the appended drawings.

It is understood that the features recited above and those yet to beexplained below are usable not only in the respective combinationindicated, but also in other combinations or in isolation, withoutdeparting from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWING VIEWS

The invention is depicted schematically in the drawings on the basis ofan exemplifying embodiment, and will be described below with referenceto the drawings.

FIG. 1 schematically shows a freeze fracture machine according to thepresent invention in a preferred embodiment.

FIG. 2 schematically shows a portion of the freeze fracture machine ofFIG. 1.

FIG. 3 schematically shows the portion of the freeze fracture machine ofFIG. 2 in a different working position.

FIG. 4 schematically shows a knife receptacle and a knife holder for afreeze fracture machine according to the present invention.

FIG. 5 schematically shows a sample receptacle and a sample holder for afreeze fracture machine according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically depicts a freeze fracture machine 100 according tothe present invention in a preferred embodiment. A door 120 having aviewing window 121 is provided on the front side. Through door 120,access is enabled to vacuum chamber 110, which is located in theinterior of the freeze fracture machine or is constituted by itsinterior. Viewing window 121, which is made e.g. of glass that isintroduced into door 120, allows observation of operations in vacuumchamber 110.

A transfer lock 130, which enables access to vacuum chamber 110, isprovided on the side of freeze fracture machine 100. A valve by whichvacuum chamber 110 can be closed off from the outside in airtightfashion is provided, for example, in transfer lock 130. A housing 131can be mounted on transfer lock 130 in airtight fashion, for example bymeans of a bayonet closure. A positioning apparatus embodied as a sliderod 135 is provided in housing 131. This slide rod 135 is arranged inhousing 131 in airtight fashion, for example by means of a seal, in sucha way that it is displaceable along its axis relative to housing 131 andis rotatable. It is part of an elastomer-sealed rotary/slidelead-through.

Once housing 131 has been mounted on transfer lock 130 in airtightfashion, and while the transfer lock, in particular the valve thereof,is still closed, the interior of housing 131 as far as the valve ispumped out, for example by means of a vacuum pump. Once a sufficientlygood vacuum is achieved, the valve or transfer lock 130 is opened tovacuum chamber 110.

By means of slide rod 135, both a sample (previously mounted thereon)and a knife can be introduced through the transfer lock into vacuumchamber 110, and likewise removed again from vacuum chamber 110.

FIG. 2 schematically shows a portion of freeze fracture machine 100, inparticular an interior view of vacuum chamber 110. A knife receptacle150, which comprises, for example, a copper block cooled with liquidnitrogen, is provided in vacuum chamber 110. Knife receptacle 150 isdisplaceable via a rail 170 between a working position and a changingposition.

Also provided is a sample receptacle 160 that is arranged at a fixedposition in vacuum chamber 110. Like knife receptacle 150, samplereceptacle 160 comprises a copper block through which liquid nitrogenflows. A cooling system for supplying knife receptacle 150 and samplereceptacle 160 with liquid nitrogen is not depicted in the interest ofclarity.

Knife receptacle 150 and sample receptacle 160 are displaceable relativeto one another in order to section or break a sample.

Visible on the right side is slide rod 135 with its vacuum-chamber-sideend on which, for example, a sample holder 161 is mounted. Samplereceptacle 160 and slide rod 135 are positioned or arranged with respectto one another in such a way that sample holder 161 can be mounted onsample receptacle 160 by moving slide rod 135 along its axis.

FIG. 3 shows the portion of freeze fracture machine 100 of FIG. 2, withknife receptacle 150 in the changing position. For this, knifereceptacle 150 is displaced horizontally and vertically along rail 150.The movement of knife receptacle 150 into the changing position (andalso correspondingly back into the working position) is accomplishedpreferably automatically by means of a corresponding control system anddrives. Manual displacement is likewise conceivable, however, forexample via a lever.

When knife receptacle 150 is in the changing position, knife receptacle150 and slide rod 135 are positioned or arranged with respect to oneanother in such a way that a knife holder mounted at the end of the axiscan be mounted on knife receptacle 150 by moving slide rod 135 along itsaxis.

FIG. 4 depicts, schematically and by way of example, a knife receptacle150 and a knife holder 151 for freeze fracture machine 100. Knifereceptacle 150 here is in the changing position shown in FIG. 3.Introduced into knife holder 151 is a holding apparatus 154 that can bemounted, for example, at one end of slide rod 135.

Knife holder 151 comprises fastening means 153 that are embodied in thepresent case as bolts impinged upon by a spring force. A knife 155 isfurthermore mounted on the underside of knife holder 151, for example bymeans of a screw connection or clamp connection. Knife holder 151 isembodied in such a way that different knife shapes and knife materialscan be mounted thereon.

Knife receiver 150 comprises receiving means 152, in the present case inthe form of two rails, on its underside. Knife holder 151 can be mountedby means of slide rod 135 on knife receptacle 150, by sliding knifeholder 151 into receiving means 152. By means of slide rod 135, orholding apparatus 154 mounted thereon, the bolts can be retractedagainst the spring force so that knife holder 151 can easily be slidinto the receiving means. A rotary mechanism, for example, in whichslide rod 135 is rotated and the bolts are thereby retracted, can beprovided for this purpose.

As soon as the knife holder is located in its target position in thereceiving means, the bolts can be released again. Depending on the exactembodiment of receiving means 152, a positive and/or nonpositiveconnection can thereby be established.

FIG. 5 depicts, schematically and by way of example, a sample receptacle160 and a sample holder 161 for freeze fracture apparatus 100. Samplereceptacle 160 here is located in the position shown in FIG. 2 or FIG.3. Introduced into sample holder 161 is a holding apparatus 164 that canbe mounted, for example, at one end of slide rod 135.

Sample holder 161 comprises fastening means 163 that in the present caseare embodied, like fastening means 153 of knife holder 151, as boltsimpinged upon by a spring force. A sample can be mounted on the upperside of sample holder 161, for example by means of a screw connection,clamp connection, or adhesive connection.

Sample receptacle 160 comprises receiving means 162, in the present casein the form of two rails, on its upper side. Sample holder 161 can bemounted by means of slide rod 135 on sample receptacle 160, by slidingsample holder 161 into receiving means 162. A sample holder 161introduced into sample receptacle 160 is depicted by way of example inFIG. 5.

The introduction of sample holder 161 into receiving means 162 of samplereceptacle 160 is accomplished in the same manner as with knife holder151 and receiving means 152 of knife receptacle 150. In particular,fastening means 163 are embodied similarly to fastening means 153.Holding apparatus 164 is likewise configured similarly to holdingapparatus 154.

The mounting of knife holder 151 and of sample holder 161 thus functionsaccording to the same principle. The only differences are thedisplacement of the knife receptacle, and knife holder 151 that is to beintroduced with a 180° rotation with respect to sample holder 161.

Removal of the knife holder and of the sample holder proceeds in reverseorder as compared with introduction. The knife holder or sample holder,optionally in a changing position that is to be established, is releasedfrom the relevant receptacle with slide rod 135, accompanied byactuation of the fastening means, and removed via transfer lock 130.

What is claimed is:
 1. A freeze fracture machine (100) comprising: a vacuum chamber (110); a sample receptacle (160) for receiving a sample to be processed, the sample receptacle (160) being arranged in the vacuum chamber (110); a knife receptacle (150) for receiving a knife (155) provided for processing of the sample, the knife receptacle (150) being arranged in the vacuum chamber (110); a transfer lock (130) through which the sample and the knife (155) are introducible into the vacuum chamber (110); a positioning apparatus (135) provided on the vacuum chamber (110), the positioning apparatus (135) being operable to introduce the sample and the knife (155) into the vacuum chamber (110) through the transfer lock (130) and position the sample and the knife (155) in the vacuum chamber (110); the sample being positionable with respect to the sample receptacle (160) by operation of the positioning apparatus (135) such that the sample is mountable on the sample receptacle (160) by operation of the positioning apparatus (135); the knife (155) being positionable with respect to the knife receptacle (150) by operation of the positioning apparatus (135) such that the knife (155) is mountable on the knife receptacle (150) by operation of the positioning apparatus (135); and a knife holder (151) for immobilizing the knife (155), wherein the knife holder (151) is mountable on the positioning apparatus (135) and is connectable to the knife receptacle (150); wherein the positioning apparatus (135) includes a slide rod removably mountable on the transfer lock (130), and the knife holder (151) is mountable at an end of the slide rod and is transferable from the end of the slide rod to the knife receptacle (150) by moving the slide rod relative to the knife receptacle (150).
 2. The freeze fracture machine (100) according to claim 1, wherein the knife receptacle (150) is positionable into a changing position, and the positioning apparatus (135) is operable to mount the knife (155) on the knife receptacle (150) when the knife receptacle (150) is at the changing position.
 3. The freeze fracture machine (100) according to claim 1, further comprising a sample holder (161) for immobilizing the sample, wherein the sample holder (161) is mountable on the positioning apparatus (135) and is connectable to the sample receptacle (160).
 4. The freeze fracture machine (100) according to claim 3, wherein the knife receptacle (150) comprises receiving means (152) for receiving the knife holder (151) to establish a connection of the knife holder (151) to the knife receptacle (150).
 5. The freeze fracture machine (100) according to claim 4, wherein the sample receptacle (160) comprises receiving means (162) for receiving the sample holder (161) to establish a connection of the sample holder (161) to the sample receptacle (160).
 6. The freeze fracture machine (100) according to claim 4, wherein the receiving means (152) for receiving the knife holder (151) and the receiving means (162) for receiving the sample holder (161) each include two spaced apart rails.
 7. The freeze fracture machine (100) according to claim 5, wherein the knife holder (151) comprises fastening means (153) corresponding to the receiving means (152) of the knife receptacle (150), wherein the fastening means (153) of the knife holder (151) are actuatable by operation of the positioning apparatus (135) to establish the connection of the knife holder (151) to the knife receptacle (150).
 8. The freeze fracture machine (100) according to claim 7, wherein the sample holder (161) comprises fastening means (163) corresponding to the receiving means (162) of the sample receptacle (160), wherein the fastening means (163) of the sample holder (161) are actuatable by operation of the positioning apparatus (135) to establish the connection of the sample holder (161) to the sample receptacle (160).
 9. The freeze fracture machine (100) according to claim 8, wherein the fastening means (153) of the knife holder (151) and the fastening means (163) of the sample holder (161) each include bolts.
 10. The freeze fracture machine (100) according to claim 1, wherein the sample receptacle (160) is arranged at a fixed position in the vacuum chamber (110).
 11. The freeze fracture machine (100) according to claim 1, wherein the positioning apparatus (135) is configured to displace the sample or the knife (155) inside the vacuum chamber (110) along an axis.
 12. The freeze fracture machine (100) according to claim 1, wherein the slide rod is removably mountable on the transfer lock (130) by way of a housing (131) in which the slide rod is provided. 